Rocco was listed by Pentangeli as a caporegime in Michael's family, but after the hearings turned out to be a major fiasco due to Pentangeli, he was deemed an unreliable source. Therefore, law enforcement could only presume that Michael was behind the murder of Roth.
Sonny, of course Michael would have an alibi that would protect him against being arrested in connection with Roth's murder. The greater danger to Michael would be renewal of speculation about Michael's Mob ties so soon after the Senate hearings. At minimum, police associating Rocco with Michael because of the FBI chart would question him, and the news media would have a field day with speculation.
While there might not be legal consequences for Michael, he could run afoul of the Nevada Gaming Commission. The Commission was formed in 1958 to try to "clean up" Nevada's gaming image because it had been exposed as being run by the Mob. The Commission had a "Black Book"--a list of people who could be barred from even entering a casino, much less owning or operating one. They could be barred even if they didn't have a criminal record--just unsavory reputations and associations could get someone listed in the Black Book. Michael could have lost his casino holdings simply because his caporegime, Rocco, murdered someone. (
N.B.: The Gaming Commission took away Frank Sinatra's holdings in the Cal-Nevada Lodge because he let Chicago Mob boss Sam Giancana stay there.)
